# Two dimensional electron gas in the $\delta$-doped iridates with strong spin-orbit coupling: La$_\delta$Sr$_2$IrO$_4$

## TL;DR

This study predicts a spin-orbital entangled two-dimensional electron gas at the interface of La-doped Sr$_2$IrO$_4$, revealing new electronic and magnetic phenomena with potential device applications.

## Contribution

The paper introduces a density-functional prediction of a 2DEG in La$_ ext{delta}$Sr$_2$IrO$_4$, highlighting the formation of a metallic interface with unique magnetic and electronic properties.

## Key findings

- Formation of a 2DEG at the La-doped interface.
- Partial occupation of the $J_{eff}=1/2$ upper Hubbard band.
- Presence of both electron and hole pockets in the Fermi surface.

## Abstract

Iridates are of considerable current interest because of the strong spin-orbit coupling that leads to a variety of new phenomena. Using density-functional studies, we predict the formation of a spin-orbital entangled two-dimensional electron gas (2DEG) in the $\delta$-doped iridate La$_\delta$Sr$_2$IrO$_4$, where a single SrO layer is replaced by a LaO layer. The extra La electron resides close to the $\delta$-doped layer, partially occupying the $J_{\rm eff}= 1/2 $ upper Hubbard band and thereby making the interface metallic. The magnetic structure of the bulk is destroyed near the interface, with the Ir$_0$ layer closest to the interface becoming non-magnetic, while the next layer (Ir$_1$) continues to maintain the AFM structure of the bulk, but with a reduced magnetic moment. The Fermi surface consists of a hole pocket and an electron pocket, located in two different Ir layers (Ir$_0$ and Ir$_1$), with both carriers derived from the $J_{\rm eff}= 1/2 $ upper Hubbard band. The presence of both electrons and holes at the $\delta$-doped interface suggests unusual transport properties, leading to possible device applications.